c.1200, "free from duplicity, upright, guileless; blameless, innocently harmless," also "ignorant, uneducated; unsophisticated; simple-minded, foolish," from Old French simple (12c.) "plain, decent; friendly, sweet; naive, foolish, stupid," hence "wretched, miserable," from Latin simplus, variant of simplex "simple, uncompounded," literally "onefold" (see simplex). Sense of "free from pride, humble, meek" is mid-13c. As "consisting of only one substance or ingredient" (opposite of composite or compounded) it dates from late 14c.; as "easily done" (opposite of complicated) it dates from late 15c.

From mid-14c. as "unqualified; mere; sheer;" also "clear, straightforward; easily understood." From late 14c. as "single, individual; whole." From late 14c. of clothing, etc., "modest, plain, unadorned," and of food, "plain, not sumptuous." In medicine, of fractures, etc., "lacking complications," late 14c. As a law term, "lacking additional legal stipulations, unlimited," from mid-14c.

In Middle English with wider senses than recently, such as "inadequate, insufficient; weak, feeble; mere; few; sad, downcast; mournful; of little value; low in price; impoverished, destitute;" of hair, "straight, not curly." As noun, "an innocent or a guileless person; a humble or modest person" (late 14c.), also "an uncompounded substance." From c.1500 as "ignorant people."

late 14c., "singleness of nature, unity, indivisibility; immutability," from Old French simplicite (12c., Modern French simplicité), from Latin simplicitatem (nominative simplicitas) "state of being simple, frankness, openness, artlessness, candor, directness," from simplex (genitive simplicis) "simple" (see simplex). Sense of "ignorance" is from c.1400; that of "simplicity of expression, plainness of style" is early 15c.

Middle English also had simplesse, from French, attested in English from mid-14c. in sense "humility, lack of pride," late 14c. as "wholeness, unity;" c.1400 as "ignorance."

"simple, plain, not compound," 1844, from simple (adj.) + -istic. From 1867 as "over-simple, trying to explain too much by a single principle." Also (1860) "of or pertaining to simples" (herbs used in healing, medicine of one ingredient only; the notion being that each herb possesses a particular virtue, thus a "simple" remedy), from simplist "one who studies simples" (1590s; see simple (adj.)) + -ic.

1520s, "one who simulates," irregularly formed (perhaps on the model of similar) from Latin simulare "to make like, imitate, copy, represent," from stem of similis "like" (see similar). As an adjective, "simulated," from 1610s.

1620s, "feigned," past participle adjective from simulate (v.). Meaning "imitative for purposes of experiment or training" is from 1966 (agent noun simulator in the related sense dates from 1947; also see simulation). In commercial jargon, "artificial, imitation" by 1942.

1650s, from Medieval Latin simultaneus, perhaps from simultim "at the same time," extended from Latin simul "at the same time" (see similar (adj.)), or from simul with ending abstracted from Late Latin spontaneus, where the -t- is organic. Related: Simultaneously.

The semantic development is via notion of "to be truly the one (who is guilty)," as in Old Norse phrase verð sannr at "be found guilty of," and the use of the phrase "it is being" in Hittite confessional formula. The same process probably yielded the Latin word sons (genitive sontis) "guilty, criminal" from present participle of sum, esse "to be, that which is." Some etymologists believe the Germanic word was an early borrowing directly from the Latin genitive. Also see sooth.

Sin-eater is attested from 1680s. To live in sin "cohabit without marriage" is from 1838; used earlier in a more general sense. Ice hockey slang sin bin "penalty box" is attested from 1950.

Old English syngian "to commit sin, transgress, err," from synn (see sin (n.)); the form influenced by the noun. Compare Old Saxon sundion, Old Frisian sendigia, Middle Dutch sondighen, Dutch zondigen, Old High German sunteon, German sündigen "to sin." Form altered from Middle English sunigen by influence of the noun.

early 15c., synnes, from sithenes "since," from sithen (plus adverbial genitive -es), from Old English siððan "afterward, from now on, hereafter, further, later, as soon as, after that," originally sið ðan "after that," from sið "after" (see sith) + ðan, weakened form of ðam, dative of ðæt (see that).

As a conjunction from late 14c.; as a preposition from 1510s; "from the time when," hence "as a consequence of the fact that." Modern spelling replaced syns, synnes 16c. to indicate voiceless final -s- sound. Since when? often expressing incredulity, is from 1907.

1530s, "pure, unmixed," from Middle French sincere (16c.), from Latin sincerus, of things, "whole, clean, pure, uninjured, unmixed," figuratively "sound, genuine, pure, true, candid, truthful," of uncertain origin. Ground sense seems to be "that which is not falsified." Meaning "free from pretense or falsehood" in English is from 1530s.

There has been a temptation to see the first element as Latin sine "without." But there is no etymological justification for the common story that the word means "without wax" (*sin cerae), which is dismissed out of hand by OED and others, and the stories invented to justify that folk etymology are even less plausible. Watkins has it as originally "of one growth" (i.e. "not hybrid, unmixed"), from PIE *sm-ke-ro-, from *sem- "one" (see same) + root of crescere "to grow" (see crescent).

from Sanskrit Simhapuram "Lion City," from simhah "lion" + puram "city," from PIE *pele- "citadel, fortified high place" (see polis (n.)). The name is perhaps metaphoric of something, as no lions are found there. Singapore sling attested from 1930; said on the island to have been invented there 1915 by a barman named Ngian Tong Dron.

Old English sengan "to burn lightly, burn the edges" (of hair, wings, etc.), from Proto-Germanic *sangjanan (cognates: Old Frisian of-sendza, Middle Dutch singhen, Dutch zengen, Old High German sengan, German sengen "to singe"). The root is said to be related to that of sing (v.), on the idea of some sort of sound produced by singeing (Century Dictionary), but Klein's sources reject this. Related: Singed; singeing. Singed cat "person whose appearance does not do him justice, person who is better than he looks" is from 1827.

common surname and middle name in North India, later (1699) adopted by Sikhs as a title after their initiation ceremony, also a surname adopted by male Sikhs; 1620s in English, from Hindi Singh, from Sanskrit simhah "lion."

early 14c., "unmarried," from Old French sengle, sangle "alone, unaccompanied; simple, unadorned," from Latin singulus "one, one to each, individual, separate" (usually in plural singuli "one by one"), from sim- (stem of simplus; see simple) + diminutive suffix. Meaning "consisting of one unit, individual, unaccompanied by others" is from late 14c. Meaning "undivided" is from 1580s. Single-parent (adj.) is attested from 1966.

c.1400, "unmarried person," mid-15c., "a person alone, an individual," from single (adj.). Given various technical meanings from 16c. Sports sense is attested from 1851 (cricket), 1858 (baseball). Of single things from 1640s. Meaning "one-dollar bill" is from 1936. Meaning "phonograph record with one song on each side" is from 1949. Meaning "unmarried swinger" is from 1964; singles bar attested from 1969. An earlier modern word for "unmarried or unattached person" is singleton (1937).

"to separate from the herd" (originally in deer-hunting, often with forth or out), 1570s, from single (adj.). Baseball sense of "to make a one-base hit" is from 1899 (from the noun meaning "one-base hit," attested from 1858). Related: Singled; singling.